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Biomedical subjects

W Wallace

Publications and source records attributed to W Wallace.

64 records · Page 4Linked to original sources
PubMed1969

Nitrite oxidase and nitrate reductase in Nitrobacter agilis.

Nitrite oxidase and nitrate reductase in Nitrobacter agilis were shown to be separate enzymes. The best separation of the two systems was achieved by ammonium sulphate fractionation. The effects of various compounds, including antimycin A, 2-n-heptyl-4-hydroxyquinoline N-oxide and chlorate, also clearly distinguish between the two enzyme reactions. The relationship between the two opposing reactions in Nitrobacter is discussed.

Antimycin A↗
PubMed1968

Properties of some reductase enzymes in the nitrifying bacteria and their relationship to the oxidase systems.

The reductase enzymes in Nitrosomonas and Nitrobacter were studied under anaerobic conditions when the oxidase enzymes were inactive. The most effective electron-donor systems for nitrate reductase in Nitrobacter were reduced benzyl viologen alone, phenazine methosulphate with either NADH or NADPH, and FMN or FAD with NADH. Nitrite and hydroxylamine reductases were found in both nitrifying bacteria, and optimum activity for each enzyme was obtained with NADH or NADPH with either FMN or FAD. The product of both these enzymes was identified as ammonia. In extracts of Nitrosomonas the ammonia was further utilized by an NADPH-specific glutamate dehydrogenase. (15)N-labelled nitrite, hydroxylamine and ammonia were rapidly incorporated into cell protein by Nitrosomonas, and Nitrobacter in addition incorporated [(15)N]nitrate. Relatively gentle methods of cell disruption were compared with ultrasonic treatment, to enable a more exact study to be undertaken of the intracellular distribution of the oxidase and reductase enzymes. The functional relationship of these opposing enzyme systems in the nitrifying bacteria is considered.

Ammonia↗
PubMedDate not supplied

Efficacy of botulinum toxin in chronic anal fissure.

BACKGROUND: Chronic anal fissures (CAF) are caused by anal sphincter hypertonia leading to an ischaemic ulcer. By inducing temporary sphincter relaxation, botulinum toxin (Botox) injection has been shown to heal CAF in approximately 73-96% of cases in clinical trials. AIM: This study looks at the efficacy of Botox clinical practice. METHODS: The medical charts were reviewed of all patients with CAF treated with Botox (30iu injected into the sphincter complex in three 10iu aliquots) in the Ulster Hospital, Dundonald, Northern Ireland between March 1999 and November 2001. RESULTS: Fifty-one charts were identified. Four patients failed to attend for review and were excluded from the study. Of the remaining 47 patients, 37 (78.7%) were healed following Botox injection. 10 out of 37 (27.0%) developed a recurrent CAF after a median time of 16.0 months (IQR 3.8-20 months). Eight of these patients opted for repeat Botox injection, which was successful in 7 (87.5%) cases. No adverse effects were reported. CONCLUSION: Botox injection for the treatment of CAF is as effective in clinical practice as reported in clinical trials from specialist centres.

Adult↗
PubMedDate not supplied

The effects of medical group practice organizational factors on physicians' use of resources.

Few studies have systematically examined the influence of physician, patient, and practice characteristics on physician-directed use of resources within the overall environment of medical group practices and none have included the practice culture in the analysis. This study analyzes the effects of the structure and culture of medical group practices on the amount of resources used to manage uncomplicated hypertension episodes of care for enrollees in a Minneapolis/St. Paul HMO during 1990. Three findings emerged from this study: (1) resource use for a well-defined episode of care varies much more than one would expect in this highly competitive managed care environment; (2) the culture of the group practice appears to be more important than organizational structure in determining resource use for the treatment of hypertension; and (3) together the culture and structural variables only explain 8 percent of the variance in resource use. The study indicated that medical group practice organizations have less influence on physicians' practice styles than expected. The group practices studied are all located in a highly competitive managed care environment and these conditions should be causing them to create more standardized practice styles among their physicians. However, wide variations in individual physician practice styles account for most of the differences observed. Either much of the unexplained variance in resource use for this episode of care results from unobserved patient and illness characteristics, or managed healthcare is not yet causing medical group practices in Minnesota to challenge physicians' individualistic practice styles.

Cost-Benefit Analysis↗
PubMedDate not supplied

The effect of tubing length, gas flow, and number of heaters on maximum gas temperature for aerosol circuits used for cold water near-drowning or hypothermia.

BACKGROUND: Clinicians who treat patients suffering from cold water near-drowning or hypothermia routinely warm inspire gases greater than body temperature in accordance with care guidelines promulgated by the various organizations. However, humidifiers are designed to prevent heating gases beyond 41 C (assuming the use of a standard six foot aerosol circuit) in order to meet International Standards Organization regulations (ISO). Clinicians must modify equipment in order to deliver care. There are several factors, which can effect the highest temperature that a particular circuit will achieve. Among the factors that are considered most important for maximum circuit are tubing length, gas flow, and the number of heaters (heat source). METHODS: The maximum temperature that a circuit could achieve was measured after varying tubing lengths (1.5 feet, 3 feet, and 6 feet), gas flow (opening or closing a venturi receiving a fixed flow rate of 10 L/min), and the size of the heat source (one or two heated humidifiers in aerosol circuit). A total of ten runs were made in each of the possible twelve combinations. RESULTS: Univariate statistics showed significant differences for Venturi open/close (p = .0001) and the number of heaters (p = .0001) but not the tubing length (p = 0.19). However, the multivariate analysis revealed significance for tubing length, number of heaters, and venturi open/closed (p = .01). CONCLUSION: All factors (tubing length, number of heaters, and tubing length) were important determinants of maximum gas temperature. The effect of tubing length can be overwhelmed by higher gas flows.

Analysis of Variance↗
PubMedDate not supplied

Does it make sense to heat gases higher than body temperature for the treatment of cold water near-drowning or hypothermia? A point of view paper.

There appears to be several areas of concern relating to the continued use of heating gases higher than body temperature for the treatment of cold water near-drowning. The use of heated gases as a primary means to rewarm a hypothermic patient does not seem to be any more effective than doing nothing at all. These low rewarming rates translate into some very long resuscitations. Even Dr. Nemiroff, who was a strong advocate of using heated humidified gases for treating cold water near-drowning, did not consider the use of warm inspired gases to be a primary rewarming technique. He referred to the use of heated humidified gases as a, "stabilization technique". However, does it make sense to use a technique that is several times slower than other methods of similar complexity? Does it make sense to use a protocol that may in fact lower a hypothermic patient's basal metabolic rate? There are some major patient safety issues raised by heating gases to high levels. However, there have not been many patients with documented airway damage. I have several hypothesis about why this is so. Few people seem to know how to significantly heat their patient's circuit. If they devise a system that gets to the therapeutic range they usually have second thoughts when the bag-valve-mask is too hot to hold, or the plastic wide bore tubing begins to melt, they will reduce the system temperature on that basis alone. Many of the hypothermic patients who are intubated simply do not have good survival rates, and so we may underestimate the degree of airway damage that occurs. Spontaneously breathing patients will tend to refuse to breathe hot gases which limits their potential for airway damage. However, is this a risk we need to run? Would it not make more sense to heat the inspired gases to close to body temperature and avoid the problem? I feel that the time has come for the Respiratory Therapy community to come together and work on this problem. The researchers have done their jobs in providing us with reasonable data on which to base a clinical decision. It would seem to me that if a Clinical Practice Guideline for cold water near-drowning or hypothermia were in place it might provide the other groups impetus for updating their guidelines. The bottom line is that patients deserve the best care that we know how to provide, and a clear set of guidelines is an essential first step.

Attitude of Health Personnel↗
PubMedDate not supplied

The use of exhaled carbon monoxide for the diagnosis of carbon monoxide poisoning. A case report.

INTRODUCTION: Carbon monoxide (CO) poisoning is difficult to confirm in small rural hospitals that lack easy access to a cooximeter. A small hand held device can be used to assess exhaled CO (ECO) in parts per million. This device is often used in smoking cessation clinics to confirm that a person has abstained from smoking. CASE SUMMARY: A 47-year-old white male became dizzy and had a near syncopal episode while working on his boat in the local marina. He was brought to the ER and was found to have an exhaled CO level of 180 ppm. The presence carboxyhemoglobin (HbCO) was confirmed later by an independent reference laboratory and the result was 26% HbCO. DISCUSSION: The patient's exhaled CO level dropped slower than expected while breathing oxygen delivered by a non-rebreather mask. This could be due to inadequate compliance to oxygen therapy and a fiO2 somewhat less than 1.0. Another limitation of the technique is the calibration gas (50-ppm CO). This concentration may be too low to assess ER patients. Therefore a confirmatory ABG with cooximetry should be obtained if available. Clinicians are cautioned that there is no safe level of HbCO (6). There is a simple formula to convert ECO to HbCO. The use of exhaled CO monitoring may be a promising alternative that is relatively less expensive than cooximetry in the ER setting, but more research is clearly indicated.

Breath Tests↗